Large networks like the Internet, enterprise networks, metropolitan area networks, and cellular networks transport information using packets that are routed and switched through various segments of a network. Within these networks, users are provided with a plurality of user applications. User applications are becoming increasingly more complex, and the amount of data generated by these applications is increasing at an exponential rate. To accommodate user demand for data intensive applications, only two options exist. The first option entails increasing the capacity of existing networks, by adding more equipment to the infrastructure. This approach is not only expensive, but it also requires a significant amount of network downtime in order to properly install and troubleshoot the addition of new hardware and software to existing network infrastructure. The second option includes developing techniques to optimize the performance of the existing infrastructure.
Several traffic control techniques have been implemented to address this problem. The most rudimentary traffic control technique discards packets if the network is congested. More advanced techniques, including Transmission Control Protocol (TCP), and several variants of TCP use a sliding window that limits the total number of unacknowledged packets in transit from end-to-end. TCP, however, treats all network packets the same, which can result in an increase in the number of dropped packets as the number of connections increases. Each connection established between devices represents a connection established by an individual application. For example, a user might be using a downloading-software updates for a word processor, using an email client, using a web browser, hosting a website, streaming multimedia (e.g., video or audio), using an instant messaging program, running a virtual desktop program, etc. In this scenario, it is possible that eight or more different connections are formed.
In a virtual environment, however, a single machine can host applications for multiple users utilizing the same services. This results in a significant increase in the total volume of data, and the number of connections needed to support the required bandwidth of each application requesting access to the Internet. To ensure that data is successfully transmitted, techniques for organizing and prioritizing packets from different applications and different users can be used to ensure that the packets are not discarded. One way of dealing with this issue is to create a set of traffic classes that prioritize packets based on a set of metrics.